I’ve come across what I think is not only a brilliant idea, but would come in darn handy. The Apple iMacs have beautiful screens. It would be awesome to have a way to use the built in monitor as an external monitor for, say, a laptop or desktop (Mac or PC). This would let you consolidate a multi-system environment saving the space you’d use for a monitor.
What would be even better would be a way to use the keyboard and mouse you have plugged into your iMac on your additional desktop or laptop. A built-in KVM switch of sorts.
I replace my monitors at work and home with iMacs. Extra systems always come in handy.